This invention relates to spring fasteners characterized by a structure having a cavity in which an extension or rib of a first part, such as a plastic panel for example, may be engaged, and they are also suitable to be engaged reversibly in a slot of second part, such as a metal sheet or the frame of a car for example. The invention also pertains an assembly of the first and the second part as connected to each other through the fastener, as well as vehicles comprising such assemblies.
A number of fasteners have been used in the past for securing one object on another object, as for example, securing an article such as for example a plastic sheet on a metal or other rigid plastic sheet. However, the fasteners of the type, which are improved by the advances of the present invention, and being used presently, have a rather low ratio of insertion force to removal force. In other words, they require considerable force to be inserted into a slot in order to provide adequate removal resistance in order to be removed from the slot. This is ergonomically inferior performance, and the operators may suffer miscellaneous ailments, while productivity is also considerably undermined.
Examples of conventional fasteners are disclosed in U.S. Pat. No. 5,987,714 (Smith); U.S. Pat. No. 5,887,319 (Smith); U.S. Pat. No. 5,542,158 (Gronau et al.); U.S. Pat. No. 5,422,789 (Fisher et al.), U.S. Pat. No. 5,373,611 (Murata); U.S. Pat. No. 5,314,280 (Gagliardi); U.S. Pat. No. 5,095,592 (Doerfling); U.S. Pat. No. 4,792,475 (Bien); U.S. Pat. No. 4,683,622 (Ohelke); U.S. Pat. No. 4,609,170 (Schnabl); U.S. Pat. No. 4,245,652 (Kelly et al.); U.S. Pat. No. 3,864,789 (Leitner); U.S. Pat. No. 3,673,643 (Kindell); U.S. Pat. No. 3,525,129 (Holton); U.S. Pat. No. 2,825,948 (Parkin); U.S. Pat. No. 2,607,971 (Bedford, Jr.); U.S. Pat. No. 2,542,883 (Tinnerman); U.S. Pat. No. 2,329,688 (Bedford, Jr.); U.S. Pat. No. 2,322,656 (Murphy), among others.
U.S. Pat. No. 5,919,019 (Fisher) provides fasteners which can only be permanently installed into a slot; they can only be inserted but not extracted without damage to parts of the fastener. The major engagement is performed by spring strips, while frictional portions of the fastener pass through the slot with at most slight compression, and immediately after the insertion of the fastener they are located in slightly spaced or barely contacting relation with the edges of the slot. They are only activated for engagement after the insertion of a bolt into a hole at the base plate. Thus, the profound effect of the increased removal to insertion ratio (explained in detail hereinbelow) is not recognized, mentioned, or implied. Thus, the intentionally provided distance of the frictional portions away from the edges of the slot by Fisher, during insertion and before use of the bolt, teaches actually away from the instant invention, which recognizes and takes full advantage of the increased removal to insertion ratio by an engagement region having a hindrance portion. As a matter of fact, if the engagement surfaces of the instant invention were located in slightly spaced or barely contacting relation with the edges of the slot, no engagement at all would take place upon insertion of the fastener of this invention into the slot.
U.S. Pat. No. 6,141,837 (Wisniewski) describes a spring fastener comprising bulbous and outwardly projecting portions, which assist in preventing withdrawal of the clip and associated molding from an aperture of a vehicle frame. However, xe2x80x9cbulbous projectionsxe2x80x9d are necessarily voluminous, take most of the space between the xe2x80x9creverse bentsxe2x80x9d, and unless they are manufactured within tight tolerances with regard to the thickness of the frame, the xe2x80x9cbase platesxe2x80x9d do not sit on the frame (see also the Figures), rendering the structure unstable.
U.S. Pat. Nos. 6,203,240 B1 (Hironaka et al.), 5,129,768 (Hoyle et al.), 5,092,550 (Bettini), 4,981,310 (Belissaire), 4,712,341 (Harris, Jr. et al.), 4,595,325 (Moran et al.), 4,431,355 (Junemann), 4,133,246 (Small), and 2,424,757 (F. Klump, Jr.) are directed to plastic or metal fasteners which are designed to be just inserted into the slot of a panel, but not extracted without damage to the fastener (if such extraction would be attempted from the front side; the side from which the fastener is inserted into the panel, since the back part of the panel is not reachable in the cases, wherein such types of fasteners are used).
As aforementioned, this invention relates to spring fasteners characterized by a structure having a cavity in which the rib of a first part, such as a plastic panel for example, may be engaged, and they are also suitable to be engaged reversibly in a slot of second part, such as a metal sheet or the frame of a car for example. The invention also pertains an assembly of the first and the second part as connected to each other through the fastener, as well as vehicles comprising such assemblies.
More particularly, the invention pertains a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising first barbs having first front ends, and a first engagement spring, the first engagement spring connected to the first side in the vicinity of the bottom portion, the second side comprising second barbs second front ends, and a second engagement spring, the second engagement spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs having a recess and a free end in the vicinity of the top portion, each spring also comprising a peak and an engagement region with a hindrance portion between the recess and the peak, the hindrance portion providing increased removal force, when the fastener is pulled by a rib of a first part engaged to the first and second barbs, after the fastener has been inserted into a slot of a second part, the slot having a slot width and edges on which edges the engagement region is engaged, the increased removal force being due to the hindrance portion, and wherein the fastener can be extracted when pulled by the rib without damage to said fastener.
This invention further pertains an assembly comprising:
a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising first barbs having first front ends, and a first engagement spring, the first engagement spring connected to the first side in the vicinity of the bottom portion, the second side comprising second barbs second front ends, and a second engagement spring, the second engagement spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs having a recess and a free end in the vicinity of the top portion, each spring also comprising a peak and an engagement region with a hindrance portion between the recess and the peak;
a first part comprising a rib inserted into the cavity of the spring fastener and engaged to the first and second barbs; and
a second part comprising a slot, the slot having a width and edges, the fastener being disposed in the slot in a manner that the edges of said slot are engaged to the engagement regions of the spring fastener;
with the requirement that by pulling the rib, the fastener is extracted from the slot without damage to the fastener, and with a higher force than a force required in the absence of the hindrance portion.
In addition, this invention is related to a vehicle which comprises an assembly, the assembly comprising vehicle comprising an assembly, the assembly comprising:
a spring fastener comprising a first side and a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side, a bottom portion wherein the first side and the second side are connected, and a top portion, the first side comprising first barbs having first front ends, and a first engagement spring, the first engagement spring connected to the first side in the vicinity of the bottom portion, the second side comprising second barbs second front ends, and a second engagement spring, the second engagement spring connected to the second side in the vicinity of the bottom portion, each of the first and second engagement springs having a recess and a free end in the vicinity of the top portion, each spring also comprising a peak and an engagement region with a hindrance portion between the recess and the peak;
a first part comprising a rib inserted into the cavity of the spring fastener and engaged to the first and second barbs; and
a second part comprising a slot, the slot having a width and edges, the fastener being disposed in the slot in a manner that the edges of said slot are engaged to the engagement regions of the spring fastener;
with the requirement that by pulling the rib, the fastener is extracted from the slot without damage to the fastener, and with a higher force than a force required in the absence of the hindrance portion.
According to this invention, and particularly for ergonomic purposes combined with practical aspects, it is highly preferable that the force to insert the rib of the first part into the cavity of the spring fastener should be less than 40 lbs, preferably less than 15 lbs, and even more preferably less that 10 lbs; the force to insert the spring fastener into the slot should be less that 30 lbs, preferably less than 15 lbs, and even more preferably less than 10 lbs; and the force to extract the spring fastener from the slot should be in the range of 30-100 lbs, and preferably in the range of 50-70 lbs.
To achieve the above results, in a preferred embodiment of this invention, the hindrance portion comprises one structure selected from ripple, side rib, upward solid bent extension parallel to the peak and the recess, knurled region, bent teeth, each having a depth, and a combination thereof.
It is preferable that the depth of the ripple, the side rib, the upward solid bent extension which is parallel to the peak, the knurled region, and the bent teeth is smaller than 0.2 mm.
It is further preferable that each ripple is in the form of a depression, the depression having a deepest part, a front side, a back side and a width, and the hindrance portion has a surface, comprises not more than three ripples, and wherein the depth of each ripple is the distance between the surface of the hindrance portion and the deepest part of the respective ripple.
It is more preferable that the hindrance portion comprises not more than two ripples, and even more preferable one ripple.
For better performance, the ripple width is larger than the depth of the ripple, and preferably the ripple width is at least twice the size of the depth of the ripple.
The ripple width is preferably in the range of 0.1 to 0.5 mm and the ripple depth is in the range of 0.01 to 0.1 mm.
In a preferred embodiment, the back side of the ripple has a slope in the range of 15 to 30 degrees with regard to the general plane of the hindrance portion, and it is also preferable that the front side has a higher slope than the back side.
In the case that the hindrance portion comprises a single ripple, it is highly preferable that the ripple has only a back side, and substantially lacks a front side. It is also highly preferable that the back side has the form of a curvature with a gradually decreasing slope. For example, the gradually decreasing slope may have the shape of an arc in the range of 50-70 degrees with a radius in the range of 0.03-0.05 mm.
The barbs are preferably selected from a group consisting essentially of:
first barbs being outer barbs and second barbs being inner barbs;
first barbs being outside outer barbs and second barbs being inside outer barbs; and
first barbs being inner barbs and second barbs being inner barbs.
It is preferable that the barbs are cut from their respective side, are flexible, and bent in the vicinity of their respective front end as described for example in U.S. Pat. No. 6,279,207 B1, which is incorporated herein by reference, and more particularly in FIG. 1 of said patent, with an angle of bent in the range of 5-25 degrees.
The barbs are considered to be flexible if they do not cause the width W3 (FIG. 1A) to increase more than 30%, preferably 20%, and more preferably 10%, when the rib 46 is inserted into the cavity 19 of the fastener 10 (FIG. 4A), and provided that the first object 46 is adequately hard to hinder the barbs 36 from substantially digging into it.
Regarding the outside outer barbs, it is preferable that their front points are at a distance from the second side smaller than the thickness of the material from which the spring fastener was made. This is to avoid interconnection of the fasteners, when said fasteners are stored in bulk.
The barbs may have variable width along their length, or they may have substantially the same width along their length. Further, the front points of the barbs may be toothed.
It is also preferable that the fastener has a width in the vicinity of the top portion of the fastener which is at least 60%, and more preferably at least 70%, as wide as the slot width.
With respect to the engagement region it is preferable that it is at least partially wider than the rest of the engagement spring.
The spring fasteners of the instant invention may have two engagement springs at the edges of each side instead of one engagement spring in substantially the middle portion of each side.
The spring fastener may further comprise additional lower barbs pointing inwardly and originating form the vicinity of the bottom portions of the first side and the second side of the fastener. In another embodiment, each side of the spring fastener has only one upper barb and one lower barb, the upper barb of one side facing the lower barb of the other side and vice versa. In still another embodiment, the fastener may further comprise a relief opening in the vicinity of the bottom of the spring fastener.
The spring fastener of the instant invention may further comprise a molded elastic body under the top portion of said spring fastener. Such arrangements are disclosed in U.S. Pat. No. 6,353,981 B1, which is incorporated herein by reference.
In another embodiment, the spring fastener of the instant invention may further comprise:
an elastic body comprised of at least a gasket, the gasket extending away from the closed cavity in the vicinity of the top portion of the fastener and enclosing at least partially the cavity; and
a casing surrounding at least partially the spring fastener under the top portion, except at least the engagement section of each engagement spring, the casing also at least partially surrounding the cavity and such portion of the elastic body which at least partially encloses the cavity;
wherein the casing has lower ultimate elongation, higher Shore hardness, and higher shear strength than the elastic body.
Such arrangements are disclosed in U.S. Pat. No. 6,381,811 B2, which is incorporated herein by reference
According to the present invention, any embodiments of fasteners described above and their equivalents may be used in any assembly in which the first part and the second part are connected with the fastener, as well as in any vehicle comprising such an assembly or such a fastener or its equivalents.